Facile synthesis of 2D/0D Bi2O3/MnO2 Z-scheme heterojunction for enhanced visible light-assisted photocatalytic degradation of acetaminophen

Abstract

The construction of heterojunctions is a prominent strategy for improving the photocatalytic activity of semiconductor nanoparticles. In this study, a novel visible-light-driven 2D/0D Bi2O3/MnO2 (BMO) Z-scheme heterojunction was fabricated through a facile room-temperature solution-phase synthesis scheme to achieve enhanced photocatalytic degradation of acetaminophen (ACT). The BMO nanocomposite achieved 94.3% degradation efficiency at 0.0202 min−1 in 120 min, approximately 3.5 and 3.8 times higher than the degradation rate of the individual MnO2 and Bi2O3 photocatalysts, respectively. Based on electron paramagnetic resonance spectra and Mott-Schottky measurements, a Z-scheme heterojunction appeared between the Bi2O3 nanoflakes and MnO2 nanoparticles. The effective charge separation and electron transfer efficiency due to Z-scheme heterojunction and a narrow band gap of 2.10 eV were responsible for the enhanced photocatalytic performance. Further, the intermediates and end products of ACT degradation were identified, and plausible degradation pathways were established. Additionally, the performance of BMO in various real water matrices was evaluated. The degradation efficiency was highest in deionized water, followed by tap water, municipal, hospital, and pharmaceutical industry wastewater. Eventually, a mathematical model based on an artificial neural network has been developed to predict the photocatalytic process. Besides, the excellent photocatalytic performance of the BMO nanocomposite remained intact even after five consecutive cycles. The results of this study elicit crucial insights into synthesizing highly efficient and stable Z-scheme heterojunction photocatalysts to degrade emerging contaminants.